Monday, 2 January 2017

10:37 – Barbara continues with her annual White Tornado house cleaning. Colin and I have to keep moving constantly to make sure we’re not dusted, cleaned, and polished because we’re mistaken for furniture.

Our weather is going to be gray, drizzly, and warmish for the next couple of days. Starting Wednesday evening, a cold front is to move in. By Friday we’re to have lows in the mid-teens F (~ -10C), with snow and freezing rain.

Dave commented on yesterday’s post:

It’s a shame that there isn’t a more cost effective battery available than the ones Bob mentioned. I’m looking at the same batteries if I get a solar setup. The only difference is I would be getting them from Menard’s instead of Home Depot. This battery on Amazon has more useful capacity than two of the batteries that Bob is looking at. Sadly it costs 50% more. If you drain conventional deep cycle batteries below half of their maximum capacity, their life is dramatically shortened. AGM batteries can put out 80% of their maximum capacity without a shortened life.

That’s a good battery, but in fact one of them is nowhere close to the capacity of two of the Exide Nautilus 31 batteries I mentioned. One of the SLR155 batteries has an Amp-hour rating of 155 Ah (at a 20 hour discharge rate), versus 230 Ah for two of the Exides; a reserve capacity of 350 minutes (at 25 Amps draw, or a total of 145 Amp-hours), versus 410 minutes (total of 171 Amp-hours) for two of the Exides; and a weight of 90 pounds, versus 124 pounds for two of the Exide Nautilus 31 batteries. And one SLR155 costs $310, versus $198 for two of the Nautilus 31s. Dollar for dollar, I could get three of the Nautilus 31s for a bit less than one SLR155, which would give me 345 Ah (versus 155 Ah for the single SLR155), 615 minutes of reserve capacity, or about 255 Ah (versus 145 Ah for one SLR155), and 186 pounds (versus 90 pounds for one SLR155).

As to battery type, AGM (absorbent glass mat) does in fact have some advantages, but it also has disadvantages. I strongly prefer FLA (flooded lead-acid). Yes, FLA requires maintenance, including regular topping off with distilled water and using a hydrometer regularly to keep an eye on battery health, but FLA has enough advantages that I think I’ll stick with it. Barbara is headed down to Winston in the next week or two to run errands, so I think I’ll ask her to pick up a couple of the Nautilus 31s.